Aircraft control



H. BAER ET AL AIRCRAFT CONTROL Filed May 1.. y192W dal@ afa/f May 3, 1938.

Passau May 3, 193s Finnegan, New York, N. Y.,

assignors to Eclipse Aviation Corporation, East Orange, N. J., a cotporation of New Jersey Application May 1. 1937, Serial No. 140,244

"ZClalmm This invention relates to aircraft, and particularly to the under-carriage, or landing gear. of aircraft.

- An object of the invention is to provide auto'- matic control of the positioning of the crafts landing gear. f

A second object isto provideautomatic control of the degree of inflation of the tires of the landing gear.

4 10 Other objects are to provide, in a motor operated landing gear system, automatic control of the energization of the landing gear motor, as

well as of the duration of such energization; to provide automatic indications, of the landing gears position, together with an inter-connecting of the indications and controls with the speed of `theaircraft propeller drive, whereby a reduction in speed causes the energization of the landing gear motor and the sounding oi?` an alarm to indicate a lack of completeness of the gear extending operation.

These and other objects of the invention will become apparent from inspection of the following specification when read with reference to l the accompanying drawing wherein is illustrated the preferred embodiment of the invention. It is to be expressely understood, however, that the drawing is `for the purpose of illustration only, and is not designed as a deiinition of the limits of the invention, reference being had to the appended claims for this purpose.

ln the drawing:-

neference character t designates an aircraft having a motor which either singly or in conjunction with additional motors and associated propellers constitute the flight sustaining means for the craft. Reference characters 8 and El designate the two type of wheels constituting the ground'contacting portion of the landing gear,

w and reference character il designates an electric motor which in conjunctionwith manually operable means I2 and a gear train indicated, in part, at I3 and 4Il, constitute the means for raising the landing gear to-the retracted position where- 45 in the wheels enter recesses` or wells in the body of the craft corresponding to the recess for the Wheel 8 which is indicated at l5, said electric motor being of a reversiblel type such as that indicated in Figs. 2 and 3 in the application of o Joseph W. Allen, Serial No. 50,229, filed November 16,V 1935, whereby the said motor isfelfective not only asia gear retracting means but also as a gear extending -means; the diierent operations being made possible by the reversibility 55 of the motor under the control of the two direc- (Cl. 244-102) V c A 'tional energizing switches I9 and 20 which are preferably located within the indicating device 2l so that movement of the rotatable element or index 22 of the said device or of some other part associated therewith, on the same rockshaft 23, 5

will cause closure of one or the other of the said directional switches, depending upon which of the two actuating solenoids 26 and 21 is energized, the said switch element being normally held in the lateral position indicated by suitable m means which is shown in the form of a centering spring 29 suitably mounted in the housing 2l.

As above indicated the invention involves the inter-connecting of engine speed responsive means with the landing gear operating and posi- 15 tion indicating means, whereby a reduction in the speed of the propelling engine of the craftsuch as that which necessarily takes place before the craft-can be successfully 'maneuvered to a landing-produces an automatic energization of the solenoid 21, which energization in turn produces first, a'movement of the index element 22 to the,down" position to indicate that the landlng gear extending mechanism is coming into operation to move the gear to its lower position; 25

secondly, to cause energization of the landing gear motor li to produce such lowering of the landing gear; and thirdly, to cause energization and operation of the-audible warning unit 3l the purpose of which is to inform the operator 30 that the lowering of the landing gear has not been completed, the actual completion vof such lowering operation being assured only' when'certain automatic control means, to be described, have functioned to produce a discontinuance of 35 the audible signal emitted by the warning unit; and fourthly, .an energization of the compressor t3, which, in conjunction with certain control elements to be described, provides an automatic regulation of the degree of iniiation--that is, of 40 thelair pressure within the inatable tubes of the tires of the landing wheels 8 and 9, the compresser 43 being connected with said tubes through suitable air hose and coupling valves, as indicated at (A) and. (B). 45

As shown the energization of the compressor is brought about by electromagnetic means operating to drivably connect the engine with the said compressor by way of a normally disengaged clutch mechanism -5I the engagement of which 50 is controlled by the solenoid 52 which like the solenoids 26 and 21, the warning unit 3l and the landing gear motor ll, 'derive their energy preferably from a common source indicated diagrammatically at M.- .55

The means for producing energization o! the solenoid 21 includes as shown, a circuit from the source 64 which may carry current to the said solenoid by way of electrical connections which include the contacts 61 and 68 adapted to be bridged by a current conducting bridge element 66 carried by the centrifugal governor mechanism 6I and movable by said mechanism into the circuit .closing position whenever the speed of the engine 6 falls to a degree corresponding to the throttle or landing speed of the craft. When this occurs current passes to the solenoid 21 by way of conductor 6I and said switch elements 51, 58 and 69, a second conductor 62, a pair of contacts 63 and 64 which Vunder the circumstances will be bridged by the member 6I (the landing gear being still in the retracted position). and additional conductors 61 and 69, the latter leading directly to the said solenoid 21 from which the current passes to ground as indicated. At the n same time a circuit in shunt with the circuit just traced may or may not be established for the purpose of energizing the compressor controlling solenoid 52, the establishment of this second circuit depending upon the the amount of pressure remaining within the tires of the .wheels 8 and 9. This pressure control of the circuit includes a pair oi' pressure operated movable contacts 8| and 8| a adapted to engage associated contacts 82 and 82a respectively, by a spring action corresponding to that of any of the well-known pressure operated switch mechanisms such as that shown in Patent 2,063,871 granted December 8, 1936 to Morgan C. French, either spring being effective to close the circuit to solenoid 62 whenever the pressure within either tire falls below a predetermined value, as would be the case it, for example, one of the tires had theretoforebeen punctured in rolling along the ground surface prior to the beginning of the crafts flight. cludes, in addition to the above described switch 6l, one or the other oi a pair of conductors 62 and 62a, the former leading to switch 82, II through conductor 90 and hence adapted to carry current whenever the switches 69 and 82, 8| are simultaneously in the closed position, and the conductor 82a being shown as leading to the switch 82a, 8Ia, and each switch being connected (by way of SI or Sla) to a common lead 92 connecting to the solenoid` 62 and ground. A thir'd branch circuit leads to the audible warning unit 3| which is shown as oi' the electromagnetic type, the Winding of its electromagnet III being energizable by a conductor 93 tapped from the conductor 61 and hence insuring energization of the said warningunit during the same period as that of the solenoid 21.

Energlzation of the solenoid 21 causes the index element 22 to move to the "down" position and closes a circuit to the landing gear motor II by way of the shunt connection I I and the contacts of the switch 20 which are closed by such movement of the index element. The resulting rotation of the motor and the gear train associated therewith produces a movement oi' the landing gear operating members I 1 and I1a along the lead screw I8 and I8a, whereupon the wheels are brought to their lowermost position for contact with the ground as the flight is terminated-the process of inilating the tires proceeding during this lowering operation by virtue of the energization of the clutch operating solenoid iir such inilationis necessary as determined by the cio-- sure of the switches 8|, 82 and/or Bla, 32a.

As soon as the wheels have reached the lower- As shown, this circuit inmost position the striker element |09 engages the switch bridging member 65 to move the latter to the open position against the closing tendency of the spring |I2 and vthereby discontinue the energization of both the solenoid 21 and the solenoid II3, th de-energization of the former permitting the opening of the motor circuit and the return of the index element 22 to the neutral or oi position, while the d e-energization of the latter causes the silencing of the warning unit, which silencing is the pilots assurance that the landing gear is in the safe extended position for a proper landing. Meanwhile the reflation of the tires will produce a reopening of the pressure operating switches 8|, 82 `and/or 8Ia, 82a and a resulting de-energization of the clutch, disengaging the compressor 43, whereupon the spring 53 will become effective to release the clutch and thereby bring the compressor to a stop. 'I'he parts will thereafter remain in the neutral positions indicated until the craft is prepared for its next ight whereupon the restarting oi' the engine 6 and the acceleration thereof to full climbing speed will draw the switch element 58 from the position indicated to the lower position in which it bridges the contacts II4 and I I5 andv thereby closes a circuit to the upper solenoid 26 of the indicator device, the circuit being by way of the said switch Ill and IIS, the conductors 6I and 66 and the said solenoid 26 to ground. Energ-ization of the said solenoid causes first themovement of the indicator pointer to the up position to close contacts of switch I9 and simultaneously therewith energization of the landing gear motor to cause its rotation in a direction opposite to that previously described, the circuit to the motor passing through` the branch connections II6 and,II1 which are now connected through the bridge element II8 and the switch contacts I2I and |22, the former being normally held closed by the spring |23 until such time as the resulting rotation of the motor operated gear train has-served to draw the wheels to the retracted positions, in which positions the said switch is moved to the open position by contact of the wheel therewith and the resulting compression of the spring I23. 'I'his action de-energizes the motor, but the circuit to the upper solenoid 26 remains closed during the ensuing normal flight of the craft, as such normal flight necessitates maintenance of a speed suiiicient to insure continued engagement of the centrifugal governor operated bridging member 59 with the contact I I4 and-contact II5 which control energization oi' the said upper solenoid. Thus the indicator pointer will continue to show the fact that the landing gear is in the retracted position until such time as the entire cycle of1 operations is repeated by the action oi slowing down the plane preparatory to termination of the fiight.

What is claimed iszl. In an aircraft, in combination with a shiftable landing gear, including inflatable tires, a gear shifting motor, a compressor, electrical means controlling energization of said motor and compressor, said electrical means including a source of current, and conductors from said source to said motor and compressor, said conductors including an engine speed responsive switch and a second switch in series therewith, said second switch being operable by the pressure of the fluid pumped into said tires by said compressor.

2. In an aircraft, in combination with a shiftable landing gear, including linflatable tires, a

gear shifting motor, a compressor, electrical 'said third switch to indicate the up" or down extreme position of said landing gear.

3. In an aircraft, in combination with a shiftable landing gear, including iniiatable tires, a gear shifting motor, means including a compressor for maintaining said tires inflated, means for energizing said motor, and means operable simultaneously with the energization of said motor to cause energization of said compressor.

, motor, said electrical 4oi current and conductors from said source to able landing gear,

4; `In an aircraft, in combination with a shiftable landing gear, including inflatable gear shifting motor, a compressor, electrical means controlling energization of said motor and compressor,'sad Aelectrical means including a source of current and conductors from said source to said motor and compressor, said conductors including an engine speed responsive switch and a second switch in series therewith, said second switch being operable by the pressure. of the uid pumped into said tires by said compressor, a third switch alsoV in series with said speed responsive switch, means movable with said third switch ,tol indicate the treme positions of said landing gear, additional means for indicating that the landing gear is in a position intermediate said extreme positions, and a fourth switch in series with said speed responsive' switch to controlqenergization of both said indicatingmea-ns.

`5. In an aircraft, in combination with a shift- `a gear shifting motor, electrical means controlling energization of said means including a source said motor, said conductors speed responsive series therewith, means movable with said. second including an engine tires, a

switch and a second s witch in switch to indicate the up and down" extreme positions of said landing gear, additional means for indicating that the landing gear is in a position intermediate said extreme positions, and a third switch in series with said speed responsive switch to control energization of` both said indicating means, said third switch being operable by movement of said landing gear.

6. In an aircraft, in combination with a shift' able landing gear, a gear shifting motor, electrical means controlling energization of said motor, said electrical means including a source oi' current and conductors from said source to said motor, said conductors including an engine speed responsive switch and a second switch in series therewith, means movable with said second switch to indicate the up and down extreme posi-L tions of said landing gear, and additional means for indicating that the landing gear is in a position .intermediate said extreme positions.

7. In an aircraft, in combination with a shiftable landing gear, a gear shifting motor, electrical means controlling .energization of said motor, said electrical means including a source of current and conductors from said source to said motor, said conductors including two pairs of contacts,` each #pair being `normally unbridged, a pair of electromagnets havinga common armature dis` armature toward it and thereby cause the other 0I said conducting plates to bridge the second pair of said contacts, to energize `said motor for counter-clockwise rotation, means operating to hold said armature midway between said electromagnets when the latter are de-energized, and a dial' surface associated with said armature to give a visible indication of theposition and movementsV of said armature, in terms of the landing gear. HOWARD BAER.

MARTIN J. FINNEGAN. 

